I already made some instruments based on these plans.
the thick backpiece is indeed difficult to find but I made it several times
from a 5mm thick board with glued on centerpiece to hold the crankshaft and
two cornerpieces to take the sides.
This construction is easier and the wood needed is easy to obtain...
if you need some other wood i can arrange womething...
more info ? mail me [EMAIL PROTECTED]
Marc Reymen
----- Original Message -----
From: "Arle Lommel" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, January 31, 2007 4:54 PM
Subject: Re: [HG] Building question
Chris' advice is quite good. You may, in addition, want to consider a
polyurethane glue (like Gorilla Glue). Some instrument makers swear by
them for building up laminates specifically. I haven't tried it myself,
but I was once in the shop of a well-known harp maker who used laminates
to build up curved surfaces. He used Gorilla Glue and a home-made vacuum
mold (the bag/chamber was made, if I recall correctly, from an old Avon
raft) to build his laminates.
The drawback to polyurethane glue is that it does foam out of any
available crack terribly when curing, so it is not a good choice if you
are working with pieces that are already cut to size where you don't want
to damage a surface getting squeeze-out off the final piece. You also
need to wet both surfaces prior to applying the glue, as polyurethane
will not harden properly without moisture.
The positive is that a glue joint with polyurethane is extremely strong
and highly unlikely to fail. I can't however, speak to its flexibility
and effects on vibration, but it didn't seem to create problems in the
harps this fellow made.
Depending on how much you are trying to glue, polyurethane may be much
more practical since you can get a bottle of Gorilla Glue from a hardware
store much more easily than a good quality hide glue.
Best,
Arle
On Jan 31, 2007, at 10:29 AM, Chris Nogy wrote:
I am hard pressed to see pieces other than a peghead that would require
lumber more than standard 4/4 or 8/4 dimension, which should be readily
available at most places that sell lumber. In the US, Woodcraft stores
have a pretty good selection, and they are in lots of major cities.
Also a supply that is often ignored is hardwood flooring companies.
But the key to laminating is and has always been to keep voids from
forming in the laminates. Use a thickness sander if you have one, or
make certain that your planer is set up well (planers are notorious for
leaving less than ideal mating surfaces. If you have to use a large
hand jointer plane to make sure your mating surfaces are perfect. I use
water-thinned aliaphatic (white carpenters, like Titebond, not white
craft like Elmers) and prime both surfaces with a thin coat, then when
it is dry, I sand them level and apply another coat of thinned glue, and
glamp with call blocks working from the center of the piece to the
outside. Good clamping pressure and clamp distribution is critical.
The reason for this is that vibrations can break down glue joints, and
where there is a void there is usually some flex in one or the other
piece that has held them apart, an active force working in the laminate.
Vibration from an instrument can start in one of these voids or pockets,
and destroy the glue joint from inside. You can end up with buzzes and
strange vibrational dynamics if you don't have a good, void free joint.
You can, and I also suggest if you have access to it, use hide glue to
make your joint - treat it the same way, prime the wood surfaces with a
thin layer, then activate it with a hot, wet cloth, add a little more
glue, and clamp from the inside out. Don't use the brown 'hide' glue in
a bottle, cook up your own, you can order it from many places. Hide
glue makes a strong joint, and it helps to dampen the vibration effects
in the wood joints, because of the thin bond line, the deep penetration,
and the flexibility of the material. There is a reason why hide glue is
so revered in instrument making - it doesn't get in the way of sound
like other glues do.
But in all honesty, you should try to find single pieces of wood. If
you can tell me what you need, I can probably round up pieces and get
them to you at a minimal cost (I probably have most of what you need in
my shop).
Hope this helps
Chris Nogy
*********** REPLY SEPARATOR ***********
On 1/31/2007 at 9:41 AM Solberg, Bennett J LCDR NMIMC wrote:
I am having trouble finding boards thick enough for some of the larger
pieces. Would it be feasible to glue two boards together to achieve a
board
of appropriate thickness and then cut it to shape? I have a neighbor
with
a
joiner and planer which should theoretically make it a good fit.
Thanks
B
